Creep-up phenomena in tungsten selective CVD and their application to VLSI technologies

The selective W-CVD produces self-alligned structures and is useful for the VLSI metallization. One of the problems using this technique is to control the encroachment that W penetrates along SiO2/Si interface. The silicon reduction of WF6was investigated in detail especially in the high temperature region. We found a perfect encroachment-free process and the W creep-up phenomena that W thin film creeps up onto the SiO2surface over patterned SiO2/Si boundary line on condition that the deposition is performed at 550°C on the patterned Si substrate with heavily doped layer. The mechanism of the phenomena and thier applications to the VLSI technologies are described in this paper.